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Inelastic electron tunneling spectrum from surface magnon and magnetic impurity scatterings in magnetic tunnel junctions...

by H. X. Wei, Q. H. Qin, Q. L. Ma, Xiaoguang Zhang, X. F. Han
Publication Type
Journal
Journal Name
Physical Review B
Publication Date
Page Number
134436
Volume
82
Issue
13

Analytic expressions for contributions to the inelastic electron tunneling spectrum (IETS) from surface magnon scattering and magnetic impurity scattering are obtained. It is shown that surface magnon scattering alone does not lead to peaks in the IETS. The peaks at small bias often observed in the IETS of magnetic junctions are due to magnetic impurity scattering, in agreement with the traditional model for zero bias anomaly. These impurity resonance peaks can sometimes split due to the impurities' magnetic coupling to the electrodes. Measurements of AlO and MgO barrier junctions yield excellent agreement to the theory. The experiment further shows that the magnetic impurities in MgO barriers are strongly coupled to the electrodes but those in AlO barriers are not magnetically coupled to the electrodes.